This question sounds like it has an obvious answer: How do you know you body is your own? Most likely, your instinctive response is that you just know. It’s your body, it’s always been there, and you’ve never had any trouble picking it out. But formally defining just how we have a sense of bodily ownership is a surprisingly complex task.
You might say that your connection to your body comes from distinguishing your body from others’. But Frédérique De Vignemont, a philosopher of cognitive science at New York University, points out that this skips the essential question. “You’re already assuming the distinction between what is yours and what is not yours,” says De Vignemont, who gave a lecture on bodily ownership at the recent Association for the Scientific Study of Consciousness conference in Buenos Aires.
Alternatively, some believe that bodily ownership comes from sensation. So, the area within which we’re able to feel, exert our senses, is the area over which we have ownership. But this idea is challenged by patients with somatoparaphrenia, a condition that means they deny ownership of their limbs—even though they have full sensation.
Perhaps bodily ownership is derived from control? By this account, whatever areas we’re able to move or influence would be considered our body. But, De Vignemont points out, those with paralysis and no control over their body do not lose their sense of bodily ownership. “Clearly we can’t say that bodily control is a necessary condition for the sense of bodily ownership,” she says.
Instead, De Vignemont argues that our sense of bodily ownership comes from the urge to protect it. “When you feel this body as your own, it’s because you’re aware that this body is a body that matters for survival,” she says. The survival instinct creates a deep desire to protect the area we have a sense of ownership over.
Answering this question, which gets to the heart of the mind’s relationship to the body, can have futuristic implications, De Vignemont says. Understanding how we relate to our physical body can help us create a body-like experience in virtual reality, she says.
It could also help amputees better embody their prosthetic limbs. And in the near future, we might even want to create additional body parts for ourselves. A third arm “could be very handy,” she says, but “how could it work?”
From a more widely-applicable clinical perspective, unravelling body ownership could help treat pain by revealing the mind’s relationship to the body as it processes pain.
It may seem baffling to try and come up with a clear argument for why a body is your own when few people have any trouble with this concept. But to truly understand bodily ownership, De Vignemont says, “It’s not enough to have awareness of the boundaries of your body. You need to ascribe a value to these boundaries.”